Fluid agitating is sometimes required under increased pressure, under reduced pressure or at high temperature in a closed space, for example in a reaction chamber, an autoclave, a rubber vulcanizer, an electric furnace, a heat treatment furnace, a culture chamber, or the like. The fluid agitating in such closed space is required to uniformly and promptly to distribute the temperature and/or the humidity thereof, or to activate the reactive fluid.
Apparatus for achieving such agitating includes a motive means, e.g. a motor or the like equipped outside of the closed space, and a rotating shaft attached to the motor, the shaft being provided with an agitating blade. The rotating shaft passes through a partition into the closed space amd stirs the fluid therein by means of the agitating blade.
With such apparatus, the hole must be formed in the partition to enable the shaft to pass through, and a seal must be provided around the shaft. A mechanical seal, a labyrinth seal, an oil seal, a gland packing or the like are generally utilized for sealing of such rotation shaft. As is well known, such shaft sealing devices are not able completely to prevent leakage of the fluid from the closed space. Where the inner pressure or the temperature of the closed space is very high, and/or where the shaft rotates at high speed, such sealing devices cannot retain their sealing ability. This lowers the reliability of the equipment using it. In fact, accidents occurred where lubricating oil, which has leaked from a double type mechanical seal into the inside of the closed space, was subject to high temperature and ignited.
Thus it was not generally possible to obtain satisfactory equipment in which fluid required to be stirred was disposed in a closed space. There are many fields, e.g. a high temperature and pressure moisture curing vessel for light bubble concrete, where the use of an agitating fluid in the closed spaced in not practiced, notwithstanding the fact that agitation of such fluid would be clearly effective and advantageous.
If a fluid agitator could be provided which substantially agitates the fluid under temperature and high pressure condition in a closed space without accidents, e.g. without leakage and/or ignition, it would be applicable for many fields of industry.